Because it can reach almost 200 miles per hour when diving for prey, the peregrine falcon has been called the fastest animal on earth.

Unfortunately, the peregrine was nearly wiped out by the mid-1960's by exposure to DDT*, habitat loss, shooting and other factors.

Thanks to recovery efforts, the peregrine is now poised to be upgraded from endangered to threatened.

Peregrine falcons that have been reintroduced into the wild have found homes in cities where they nest on ledges and sides of tall buildings. Click here for pictures. City-dwelling pigeons and starlings provide plenty of food.

*DDT was originally created in 1873. Only when its use as an insecticide was discovered in 1939, however, did it come into widespread use. The scientist who made this discovery was awarded the Nobel Prize in 1948.

After World War II, it became especially popular due to its effectiveness against mosquitoes that spread malaria and lice that carried typhus. The World Health Organization estimated that 25 million lives were saved because of its use. Problems soon surfaced, however, as many insects began to develop resistance to the insecticide. It was also discovered to be highly toxic to fish.

Because it does not break down easily, DDT builds up in the fatty tissues. Animals that ingest it, carry it for some time. It takes an animal eight years to metabolize one half of the DDT it consumes. Birds, like the bald eagle, ingested DDT after eating contaminated fish. The DDT caused the bird's egg shells to be brittle and thin and to break easily. Eggs often were broken in the nest when the parents sat on them during incubation. This was one of the reasons populations declined to dangerous levels.

DDT was banned in the United States in 1973, although it is still used in other parts of the world. Birds that migrate to other continents are still at risk. primary source:University of Oxford, Department of Chemistry